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Conversations with Albert Einstein 

R. S. Shan kl and 
Case Institute of Technology, Cleveland 6, Ohio 
(Received 11 September 1962) 

The following account of talks with Professor Einstein are the notes made by the writer in 
Princeton immediately after each of five visits about ten years ago. They were originally 
written without any thought of publication, but rather as a private record of very wonderful 
experiences. However, since they may contain matters of interest to others, it has been decided 
to publish them. 

IT was my privilege to call on Professor Ein- 
stein in Princeton on five occasions in the 
period 1950-1954. The conversations at these 
visits dealt principally with the work of Albert 
A. Michelson at Case, the Michelson-Morley 
experiment and the studies which led to clarifi- 
cation of the results obtained by Dayton C. 
Miller at Mount Wilson. These conversations 
with Einstein were a rare and inspirational 
experience, and it has been suggested that they 
might be reported so that younger physicists who 
have not met Professor Einstein personally might 
get a better impression of the kind of man he was. 
The notes are exactly as written down at the time 
except for minor changes. Consequently, the 
reader will find certain repetitions, and perhaps a 
few discrepancies. These, however, only em- 
phasize the fact that all Professor Einstein's 
comments were made from memory, often on 
events that had occurred 50 years before our 
meetings. Some references and footnotes have 
been added for clarification. 

I. 4 February 1950 

The first visit to Princeton to meet Professor 
Einstein was made primarily to learn from him 
what he really felt about the Michelson-Morley 
experiment, and to what degree it had influenced 
him in his development of the Special Theory of 

Relativity. I had not had experience in making 
appointments with such great men as Einstein, 
and I puzzled a good deal about how this should 
be done. Finally after considerable hesitation, I 
wrote directly to him stating the purpose of my 
visit and suggesting a day at the end of the New 
York meetings of the American Physical Society 
to call on him. I received an immediate reply 
from Miss Helen Dukas, Einstein's secretary, 
giving me a most friendly invitation to come to 
Einstein's office at the fnstitute for Advanced 
Study at 11 :00 a.m. on the suggested day. 

Needless to say, I was there in more than 
ample time and at last I could see him approach- 
ing on foot as was his custom. Exactly at 11 :00 
a.m. Professor Einstein finished his brisk walk 
from his home on Mercer St. to the Institute for 
Advanced Study, and after pausing to pick up 
his mail, he greeted me, shook hands and invited 
me into his office which was room 115. He was 
very friendly, informal, and courteous, instantly 
impressing one by his marvelous eyes — large, 
discerning, but above all, kindly. After first nod- 
ding me to a chair, he seated himself at his desk. 
His large office was attractively furnished but 
was completely devoid of gadgets, honors or 
mementos, although his desk was covered with 
papers, books and journals. It had an atmosphere 
of friendliness and scholarliness. 



He began by asking me to remind him of the 
purpose of my visit and smiled with genuine 
interest when I told him that I wished to discuss 
the Michelson-Morley experiment performed at 
Cleveland in 1887. When I reminded him that 
Michelson had been Professor of Physics at Case 
for eight years, he nodded. I showed him the 
drawing of the apparatus as reproduced in my 
paper. 1 He seemed greatly interested, asking me 
to sketch on his blackboard the details of their 
method of floating the stone on mercury. I was a 
little hesitant, because the blackboard was 
covered with neat equations dealing with his new 
Unified Field Theory. But he waved his pipe and 
said, "Oh rub that out!" I made some sketches, 
and he commented on them with keen interest. 
He was especially pleased with the float design 
that required the use of so little mercury. His 
eyes brightened, and he chuckled at this. He 
asked me where the parts of the apparatus are 
now located, especially the stone, and when I 
told him it had disappeared, he said, "It would 
be nice if all the parts could be brought together 

When I asked him how he had learned of the 
Michelson-Morley experiment, he told me that 
he had become aware of it through the writings 
of H. A. Lorentz, 2 but only after 1905 had it come 
to his attention! "Otherwise," he said, "I would 
have mentioned it in my paper." 8 Pie continued 

iR. S. Shankknd, Am. J. Phys. 17, 487(1949). 

2 H. A. Lorentz, Arch. Need. 2, 168 (1887), and many 
letter references. 

3 A. Einstein, Ann. Physik 17, 891 (1905) ; also in English 
translation (Dover Publications, New York). My col- 
league, Professor L. L. Foldy makes the following com- 
ment: Although Einstein may have been unaware of the 
Michelson-Morley experiment in 1905, he does make 
reference in the second paragraph of his 1905 paper to 
"unsuccessful attempts to discover any motion of the earth 
relatively to the 'light medium'." It is not clear whether 
Einstein is here referring to v/c or {v/c} 2 experiments, 
particularly since in the next sentence he goes on to say 
"They suggest rather that, as has already been shown to 
the first order of small quantities, the same laws of electro- 
dynamics and optics will be valid for all frames of reference 
for which the equations of mechanics hold good." There is 
an implication, but by no means a certainty, that the first 
reference is to second-order experiments such as the 
Michelson-Morley experiment, and suggests the possibility 
that Einstein was aware of the negative results of such 
experiments if not with the experiments themselves. 
Einstein derives the Lorentz-Fitzgerald Contraction but 
says nothing about whether there is experimental confirma- 
tion. The whole paper is rather strange in the respect that 
Einstein reveals very little about what he knows to be 
experimentally verified and in that he makes no specific 
references to the work of others. The paper in fact presents 
an enigma in that it is very difficult to see how much of the 

to say the experimental results which had in- 
fluenced him most were the observations on 
stellar aberration 4 and Fizeau's measurements 5 
on the speed of light in moving water. "They 
were enough," he said. I reminded him that 
Michelson and Morley 6 had made a very accurate 
determination at Case in 1886 of the Fresnel 
dragging coefficient with greatly improved tech- 
niques and showed him their values as given in 
my paper. To this he nodded agreement, but 
when I added that it seemed to me that Fizeau s 
original result was only qualitative, he shook his 
pipe and smiled, "Oh it was better than that!" 
He thought Zeeman's 7 later precise repetition of 
this experiment was very beautiful. He seemed 
really delighted when I mentioned to him how 
elegant I had found (as a student) his method of 
obtaining the Fresnel dragging coefficient from 
his composition of velocities law of special 

I asked Professor Einstein how long he had 
worked on the Special Theory of Relativity 
before 1905. He told me that he had started at 
age 16 and worked for ten years ; first as a student 
when, of course, he could only spend part-time on 
it, but the problem was always with him. He 
abandoned many fruitless attempts, "until at 
last it came to me that time was suspect!" Only 
then, after all his earlier efforts to obtain a theory 
consistent with the experimental facts had failed, 
was the development of the Special Theory of 
Relativity possible. 

This led him to comment at some length on the 
nature of mental processes in that they do not 
seem at all to move step by step to a solution, 
and he emphasized how devious a route our 
minds take through a problem. "It is only at the 
last that order seems at all possible in a problem." 

I showed him what I had written in the paper 
about the Michelson-Morley experiment and the 

special theory of relativity is a pure mental construct and 
how much is an inference from experimental results (or a 
theoretical formulation of them) of which Einstein had 
knowledge. See also G. Holton, Am. J. Phys. 28, 627 

4 J. Bradley, Phil. Trans. Roy. Soc. (London) 35, 637 
(1728); G. B. Airy, Proc. Roy. Soc. (London) 20, 35 
(1871); 21, 121 (1873). 

6 H. L. Fizeau, Compt. rend. 33, 349 (1851) ; Ann. Chem. 
Phys. 57, 385 (1859). 

6 A. A. Michelson and E. W. Morley, Am. J. Sci. 31, 377 

' P. Zeeman, Proc. Amsterdam Acad. 17, 445 (1914) : 18, 
398 (1915). 


Special Theory of Relativity. This he read 
eagerly, puffed at his pipe, and nodded approval. 
When I suggested that the notice given to 
Fitzgerald's contribution was perhaps a little 
overemphasized, he said, "Oh no, he had the idea 
to try to clear up the mess." 

Einstein first met Michelson in Pasadena and 
considered him "a great genius — he will always 
be thought so in this field." Einstein added that 
it was very remarkable that Michelson with 
little mathematics or theoretical training and 
without the advice of theoretical colleagues 8 
could devise the Michelson-Morley experiment. 
Michelson 's instinctive feeling for the essentials 
of a crucial experiment without completely 
understanding the related theories, Einstein con- 
sidered the surest sign of his genius. This he feels 
was in large measure due to Michelson 's artistic 
sense and approach to science, especially his 
feeling for symmetry and form. Einstein smiled 
with pleasure as he recalled Michelson's artistic 
nature — here there was a kindred bond. The 
artist was greatly in evidence in the Michelson- 
Morley experiment. Einstein remarked, "Most 
people would think the experiment silly." 9 I 
remarked on Michelson's excellent eyesight and 
the great advantage this gave him in optical 
experiments. Einstein's eyes lit up and he said, 
"Oh, but behind the eyes was his great brain!" 

I mentioned the experiments which had dis- 
proved the Ritz emission theory of light 10 especi- 
ally de Sitter's work on spectroscopic binaries 11 
and the null result obtained by D. C. Miller 12 at 

8 This is in general true, but the indirect influence of 
James Clerk Maxwell was probably decisive in directing 
Michelson's interests away from the speed of light meas- 
urements to the other problem. While at the Nautical 
Almanac Office in 1879 Michelson was able to study a letter 
from Maxwell to David Peck Todd [see Nature 21, 314 
(1880) ; Proc. Roy. Soc. (London) A30, 109 (1880)] which 
discussed basic matters on the possibility of detecting the 
earth's motion through space by optical observations. 
Professor Todd's reply to Maxwell dated May 19, 1879, has 
recently been made available to the writer through the 
courtesy of his daughter, Mrs. Millicent Todd Bingham, of 
Washington, D. C. 

9 Just as my father, F. N. Shankland; my uncle, S. D. 
Shankland; and Mr. S. S. Wilson told me that in their 
student days at Western Reserve University the Michel- 
son-Morley experiment was referred to as though it had 
been a failure, since it gave a null result. 

10 W. Ritz, Ann. Chem. Phys. 13, 145 (1908). 

»W. C. de Sitter, Proc. Amsterdam Acad. IS, 1297 
(1913); 16, 395 (1913). 

u D. C. Miller, Proc. Natl. Acad. Sci. U. S. 11, 311 

Case with the modification of the Michelson- 
Morley experiment using sunlight. He said he 
knew de Sitter well but told me he considered the 
most decisive experiment along these lines to be 
the repetition of the Michelson-Morley experi- 
ment performed with starlight at Heidelberg by 
a student of Lenard's (Tomaschek) 13 ; because 
here, the high radial velocities involved made the 
null results really decisive in establishing the 
speed of light to be independent of the motion of 
the source. Here we have the true measure of 
Einstein the man. Lenard, who along with 
Stark, was the most violently Nazi of all German 
scientists was referred to by Einstein with com- 
plete fairness and with not the slightest trace of 
malice or bitterness. 

This led him to a discussion of emission theo- 
ries of light, and he told me that he had thought 
of, and abandoned the (Ritz) emission theory 
before 1905. He gave up this approach because he 
could think of no form of differential equation 
which could have solutions representing waves 
whose velocity depended on the motion of the 
source. In this case, the emission theory would 
lead to phase relations such that the propagated 
light would be all badly "mixed up" and might 
even "back up on itself." He asked me, "Do you 
understand that?" I said no and he carefully 
repeated it all. When he came again to the 
"mixed up" part he waved his hands before his 
face and laughed, an open hearty laugh at the 

Then he continued, "The theoretical possi- 
bilities in a given case are relatively few and 
relatively simple, and among them the choice 
can often be made by quite general arguments. 
Considering these tells us what is possible but 
does not tell us what reality is." 

When I suggested that 'Ritz's theory was the 
best of the several emission theories of light, he 
shook his head and replied that Ritz's theory is 
very bad in spots. 14 But he quickly added, "Ritz 
made a great contribution when he showed that 
frequency differences are the crucial thing in 
spectral series." 

I then asked Professor Einstein if he had con- 
sidered Michelson and Gale's interferometer 

13 R. Tomaschek, Ann. Physik 73, 105 (1924). 

14 A. Einstein, Physik Z. 10, 185 (1909). 



measurement 16 of the earth's rotation important. 
He said, "Oh, yes, that is Sagnac's experiment 16 
with a small velocity and a large area." He 
thought the Michelson-Gale experiment very 
beautiful but added that "there had existed no 
theoretical doubt" as to its outcome. 

This was followed by some brief comments on 
the new unified field theory. He said that some- 
how it must also be made to include "atomicity." 
When I asked if he had any experiments in mind 
relating to the new theory he said, "No, all 
advances must now wait on great developments 
in mathematics." The solutions of the nonlinear 
partial differential equations of the theory must 
be exact to be useful, and any solution obtained 
by approximation methods, such as perturbation 
theory, would not be helpful. He felt that only 
when such rigorous solutions were obtained 
would it be possible to see how "atomistic" 
phenomena will fit into the unified field picture 
and that until this is done, the situation will 
continue to be very unsatisfactory. 

Here, Einstein made some general observations 
about atomic theory and quantum mechanics and 
said at the outset, "You know I am in disagree- 
ment with most of my colleagues on the quantum 
theory." He felt that they were not "facing the 
facts" in their present methods. In fact, he spoke 
much more strongly than this and several times 
said that they had "abandoned reason" and that 
quantum-mechanical physics "avoids reality and 
reason." He spoke several times of Bohr whom he 
greatly likes and admires but with whom he dis- 
agrees in many fundamental ways. He said that 
Bohr's thinking was very clear but that "when 
he begins to write he becomes very obscure and 
that "he thinks of himself as a prophet." Here I 
had difficulty in deciding whether Einstein was a 
bit stubborn or whether he was really convinced 

16 A. A. Michelson and H. G. Gale, Astrophys. J. 61, 137, 
140 (1925). Nature 115, 566 (1925). In this experiment, 
two beams of light were made to travel in opposite direc- 
tions in a partially evacuated pipe which enclosed a large 
area — at that time a field — now built up as the Clearing 
Industrial Area near the Chicago O'Hare airport. The 
earth's rotation affected the times of travel of the two light 
beams by amounts consistent with the predictions of both 
the special and general theories of relativity, and also the 
older aether theory. 

16 G. Sagnac, Compt. rend. 157, 708 (1910); J. phys. 4, 
177 (1914). In this experiment, two beams of light travelled 
in opposite directions in an optical system rotated at high 
speed in the laboratory. Sagnac's measurements preceeded 
the general theory of relativity. 

that quantum mechanics must change its view- 
point in a very fundamental way to make further 
progress possible. 

Our conversation then returned to the Michel- 
son-Morley experiment and the Special Theory 
of Relativity, f could not help feeling that this 
elegant special theory, the product of his youth- 
ful efforts, held the place nearest to his heart. 1 
asked him if he felt that writing out the history 
of the Michelson-Morley experiment would be 
worthwhile. He said, "Yes, by all means, but you 
must write it as Mach wrote his Science of 
Mechanics." Then he gave me his ideas on 
historical writing of science. "Nearly all his- 
torians of science are philologists and do not 
comprehend what physicists were aiming at, how 
they thought and wrestled with their problems. 
Even most of the work on Galileo is poorly done." 
A means of writing must be found which con- 
veys the thought processes that lead to dis- 
coveries. Physicists have been of little help in 
this because most of them have no "historical 
sense." Mach's Science of Mechanics, however, he 
considered one of the truly great books and a 
model for scientific historical writing. He said, 
"Mach did not know the real facts of how the 
early workers considered their problems," but 
Einstein felt that Mach had sufficient insight so 
that what he says is very likely correct anyway. 
The struggle with their problems, their trying 
everything to find a solution which came at last 
often by very indirect means, is the correct 
picture. He also expressed the highest regard for 
Laue's scientific writings. 

I referred to Einstein's visit to D. C. Miller at 

Case in 1921 ; an event which I am sure was 

decisive in Miller's work on the aether-drift 

experiments from 1921 through 1926. He told me 

that when he came to the United States that 

year, he did not know a word of English. On the 

trip he picked up some by ear, He told me, "I am 

the acoustic type ; I learn by ear and give by 

word. When I read I hear the words. Writing is 

difficult, and I communicate this way very 

badly." He added that he never really felt sure of 

the spelling of any English word. He told me that 

he even hated to write his Autobiographical Notes 

in German. 17 

17 Paul Arthur, Schilpp, Albert Einstein, Philosopher- 
Scientist (Library of Living Philosophers, Evanston, Illi- 
nois, 1949). 



My lasting memory of Professor Einstein will 
be of his kindness and courtesy, his deep respect 
for the work and personalities of others. There 
was in his manner not the slightest condescension 
but rather an earnest desire that all my questions 
be answered and that his own views or position 
be clearly stated. He told me how the day before 
he had tried "to explain simultaneity to a lay- 
man." He said, "It is very hard sometimes to 
explain these things you know." Finally, when 
all my questions were answered, we both rose and 
he walked slowly to the door with me. On leaving 
I again shook his hand and said, "Thank you 
sir." He smiled again and the great deep eyes lit 
up as he replied, "Thank you!" 

II. 17 November 1950 

Up early and to the Pennsylvania Railroad 
Station for breakfast before taking the train for 
Princeton where I arrived at 9:20 a.m. It was a 
beautiful day, and I walked first to the Nassau 
Tavern and called the Institute for Advanced 
Study where the mathematics secretary arranged 
for me to see Einstein at 11 :00 a.m. I walked to 
the Institute and after chatting with the secre- 
tary spent an enjoyable hour in the library and 
lounge. About eleven o'clock I started toward 
Einstein's office. He had arrived promptly at 
that hour, and when the secretary told him I was 
in the lounge, he started off full-tilt to get me! It 
was all the secretary could do to catch him and 
bring him back to his office door where I was 
waiting. He invited me in and after we were both 
seated, asked me about my visit. When I told 
him I wanted to tell him some of the things we 
had found in D. C. Miller's observations 18 he 
said, "Do you really think there is something in 
them?" When I replied that I felt confident that 
a thorough analysis of the observations might 
show that they were consistent with a null re- 
sult, he was all interest and excitement. We both 
got up and went to the blackboard and for an 
hour worked there, walked around the room 
while talking, sat on the table, and had a wonder- 
ful time. He was far more animated than on my 
visit in February. Several times he exclaimed to 
me, "This is very beautiful!" I told him that it 
had always been a great puzzle to me why 

18 D. C. Miller, Revs. Modern Phys. 5, 203 (1933), and 
original data sheets given by Miller to the writer. 

Miller's data seemed to yield this small positive 
result and that I had concluded that it might be 
due to his method of treating the data. On the 
blackboard I carried through a "sample run" in 
outline and explained my view that connecting 
the 16 averaged points by line segments was 
wrong. He emphatically agreed and added that 
what this really does to the data would require 
"a very complicated analysis." Then I told him 
of the Wood's Hole work on ocean wave analysis 
showing that mechanical analyses such as those 
given by Miller's Henrici Harmonic analyser 
might introduce false periods in finite sets of 
data. 19 

I outlined our plan to apply an auto-correlation 
analysis to Miller's data, and told him about the 
machine R. L. Stearns was building to carry out 
the analysis. He did not know of this method but 
immediately understood when I explained the 
process and he pointed out that it would not give 
phases and that these are more important for an 
"aether-drift" than amplitudes. This I agreed to 
but also replied that if the data seemed to give a 
null result in amplitude by this method of analy- 
sis, then the phases would not be a consideration. 
He repeated several times during our talk that 
since the phases found by Miller ("which fix the 
direction in space") were not consistent, this was 
the strongest argument against the drift reported 
by Miller. He said several times, however, that 
he (and also H. A. Lorentz) considered Miller an 
excellent experimenter and thought his data 
must be good. He emphasized that mere multi- 
plication of data is not a good thing. This re- 
inforced our resolve to concentrate on that part 
of Miller's data where he indicated "excellent 
conditions." Einstein also told me that H. A. 
Lorentz had studied Miller's work for many 
years and could not find the trouble. 

Einstein asked about strains in the interfer- 
ometer and the experimental conditions at 
Mount Wilson. He emphasized that if there is a 
systematic effect, however small, it must be 

19 Note added February 1955 : It was not until early 1954 
after the complete analysis of variance results were avail- 
able that we were convinced that the periodic effects found 
by D. C. Miller were not due to statistical fluctuations or 
to his method of analysis. Only then did we plunge deeply 
into a study of the temperature effects to find the real cause 
of Miller's results (see reference 34). The essential correct- 
ness of Miller's harmonic analysis had meanwhile been 
proved by the autocorrelation analysis carried out by R. L. 
Stearns, M. S. Thesis, Case Institute of Technology (1952). 



explained. He was most interested and encour- 
aged me to carry the problem through. 

I then told Professor Einstein about the un- 
published 1924 Case data, and he was very 
interested. He fully understood why Miller did 
not consider the null results of this work signifi- 
cant because it was done in a basement room 
where the "drag" would be large. He pointed out, 
however, that there should be nearly as much 
"drag" at Mount Wilson as in the Case basement 
room due to the mass of the interferometer 
itself. He also reminded me that any "drag" 
would be inconsistent with aberration. I told him 
that I felt the 1924 results should be published 
as these seemed to be among the best of all data 
taken in these experiments. I also told him of 
Miller's observations 18 using sunlight as a source 
and that these seemed to me to be better than 
Tomaschek's. 13 He did not protest but nodded 
agreement. He likes Tomaschek's work with 
starlight, however, because of the large radial 

We discussed the difference between the 
Morley-Miller result of 1904 and Miller's 1925- 
26 experiments. 18 He said that he had always 
been puzzled by the difference between these two 
groups of experiments. I suggested to Einstein 
that the discrepancy might be due to the method 
of analysis. 20 1 showed him at his blackboard that 
by reporting the calculated velocity of the earth 
"through the aether" (v) as given by his experi- 
ments, Miller tended to find a greater average 
speed than would be the case if he had averaged 
the amplitudes of the fringe displacements (A). 21 
Einstein agreed that our study should be con- 
fined to the experimental amplitudes and phases 
of the actual observed fringe displacements 
"until a trend was certainly established." 

Several times during our talk, Einstein said, 
"This is very nice" and laughed his hearty naive 
laugh. Several times also he asked me very 
seriously, "Why did not Miller find this?" 22 This 
seemed a great puzzle to him, one that I could 

20 Note added in June 1962-our later studies (reference 
34) make it certain that the differences were in fact due to 
the greatly differing temperature conditions existing in the 
basement laboratory at Case and at Mount Wilson. 

21 This is due to the relationship between the observed 
fringe displacements (A) and the calculated speed (v) : 
A —2L(v/c) 2 , where L is the optical path length of the 
interferometer, and c is the speed of light. 

22 Our final conclusions (reference 34) were different ! 

not resolve, but I did tell him of Miller's great 
concentration on sound and the flute in his later 
years. He asked me about Miller's acoustical 
work, and when I told him of Miller's studies of 
vowels and their relation to Helmholtz's theory, 
he was much interested. He had not realized that 
Helmholtz had done this and exclaimed "What 
that man accomplished!" I also told Einstein of 
Miller's flute collection and this seemed to inter- 
est him a great deal. 

Toward the end of our talk, I asked if Michel- 
son had ever told him how he came to invent the 
interferometer. He said no. I told him that I felt 
it had been developed in Paris while he worked 
with Jamin and Mascart. He agreed that this was 
very probable and that Michelson's basic ideas 
for the Potsdam experiment had also evolved in 
Paris. He exclaimed at one point, "How many 
ideas Michelson originated for optical research!" 
Einstein then asked me what I thought about the 
supposed variability in the speed of light. 23 I told 
him I felt it was not a real effect. 

At last I said goodbye after an hour of pleasure 
and inspiration with this great man — so kind, so 
gentle, so interested only in the truth. 

III. 2 February 1952 

I left New York on the 9:15 a.m. train and 
arrived at Princeton at 10:40. I taxied to the 
Institute for Advanced Study where the tele- 
phone girl told me that Einstein's secretary had 
called to leave word that he was coming over to 
see me. "He is expecting you," she said. At 10:55 
I saw him walking briskly along the path, from 
the direction of Oppenheimer's white house, in 
stocking cap, long coat and cigarette. He came 
in, spoke to the telephone girl and then came 
rapidly down the corridor towards his office 
where I stood. He extended his hand and very 
cordially invited me into his office (room 115). 
He had apparently put his cigarette into his coat 
pocket, and as we took off our coats he had a small 
conflagration in his. When I thanked him for 
coming over to see me he said, "I always come 
to the office." He sat down behind his desk and 
invited me to be seated. Then in a most friendly 
way he asked me, "What is your question?" 

I asked him if he had heard of the recent work 

23 R. T. Birge, Reports on Progress in Physics (The 
Physical Society, London, 1941), Vol. VIII, pp. 100-101. 



of Synge. 24 When he said no, I told him of our 
correspondence and gave an account of my 
understanding of Synge's theory relating to the 
concept of a rigid body in relativity and its 
possible bearing on Miller's results in the Michel- 
son-Morley experiment. He felt very strongly 
that Synge's approach could not be significant 
and that the results of any experiments of the 
kind proposed by Synge would be irrelevant to 
questions regarding relativity, including the 
relativistic concept of a rigid body. When I told 
him that Synge predicted a small positive effect 
due to the acceleration of the interferometer, 
Einstein asked, "What acceleration, the rotation 
of the instrument?" When I told him that I 
understood it was the acceleration due to the 
rotation of the earth on its axis through the 
possible coupling with the interferometer through 
the "pin" (assumed by Synge), he shook his head 
vigorously and replied, "This can have no con- 
nection. All such accelerations, including any due 
to Coriolis forces would be completely indis- 
tinguishable from gravity." Einstein stated 
strongly that he felt Synge's approach could have 
no significance. He felt that even if Synge de- 
vised an experiment 25 and found a positive result, 
it would be completely irrelevant. He was sure 
that all questions relating to the coupling of the 
"pin" and rigidity of the apparatus were mean- 
ingless in relativity. He emphasized, however, 
that the question of "rigidity" was most impor- 
tant and needed study. He talked at some length 
about the problem of rigidity in relativity, 
emphasizing its importance for such questions as 
the finite speed of propagation of signals, etc. 
However, he told me that no significant definition 
or theory of rigidity existed which corresponded 
to "reality," since the only rigid bodies yet 
studied were either those having zero mass or 
whose behavior could be treated in the absence 
of all external forces. 

He then referred to the fact that I had pre- 
viously told him that "Miller's positive result 
obtained at Mount Wilson could be explained by 
his method of analysis, and he felt sure that this 
was a more likely explanation than Synge's. Once 

24 J. L. Synge and G. H. F. Gardner, Nature 170, 243 
(1952); also Proc. Roy. Dublin Soc. 26, 45 (1952). 

25 Such an experiment devised by Ditchburn did in fact 
give again a null result for the aether-drift: R. W. Ditch- 
burn and O. S. Heavens, Nature 170, 705 (1952). 

again he told me that Lorentz could never explain 
Miller's result and felt that it could not be ig- 
nored, although Einstein was not sure whether 
Lorentz really believed Miller's result. 

I asked Einstein if Synge was justified in 
attacking problems regarding acceleration by 
special relativity, and he said, "Oh yes, that is all 
rightas long as gravity does notenter ; in all other 
cases, special relativity is applicable. Although, 
perhaps the general relativity approach might be 
better, it is not necessary." 

I then asked him about the speech he gave in 
Berlin on Michelson's death in 1931 and asked 
especially about his reference to the Michelson- 
Morley experiment and its relation to general 
relativity. He had apparently forgotten the 
speech, much less what he had said, so this came 
to naught. However, his eyes shone as he thought 
about Michelson and once more he referred to 
him as "an artist." When I told him that Michel- 
son's daughter (Mrs. Dorothy Michelson Stevens) 
had told me of Einstein's visit to her parents 
home in California, he smiled broadly and seemed 
to recall it with great pleasure. He was very 
complimentary about the Michelson-Gale ex- 
periment but said that at first he did not under- 
stand how it worked. 

I referred again to Synge's proposed experi- 
ment — contrasting the possible difference be- 
tween Miller's and Joos' 26 apparatus regarding 
"pin" etc., — but he just shook his head. Appar- 
ently he had completely forgotten Joos' work. 

I next asked Einstein about his early interest 
in de Broglie's work. He told me that in his 
studies of the degeneracy of gases he had worked 
out a theory for the statistical fluctuations from 
the entropy which contained "an undulatory 
term," which he identified as bearing a close 
relationship to de Broglie's ideas on matter 
waves. 27 

He went on to say that in quantum theory he 
was "in the opposition" because he felt that the 
^ functions do not represent reality. He described 
quantum mechanics as a brilliant "short-cut" 
which successfully avoided many of the difficul- 
ties and the hard work which the final correct 
theory must face and solve. He talked at length 

26 G. Joos, Ann. Physilc 7, 385 (1930); Naturwissen- 
schaften 38, 784 (1931). 

2T A. Einstein, Berliner Berichte, p. 261 (1924); p. 3 



about the i/< function description especially as 
related to a wave-packet localizing an electron to 
the extent permitted by the Uncertainty Prin- 
ciple. (He did not call it by this name nor did he 
mention Heisenberg.) Descriptions of the posi- 
tion, velocity, spreading with time of the \p 
function, etc., he did not like at all. He empha- 
sized that quantum theory only admits defining 
the position of a particle exactly by an act of 
observation which completely changes it. He 
readily admitted, however, that quantum theory 
provided the only way at present known for 
describing quantum (stationary) states. He felt 
that the if/ description was not "reality" and that 
the quantum-theory people all have a "narrow 
view" (holding his hands to his eyes to show me). 
In arguing that the quantum view was not com- 
plete, he emphasized that it had no explanation 
for the constancy of the elementary electrical 
charge. He added, however, that "it is correct to 
use quantum theory as long as it is useful, even 
though it is not a complete description." He told 
me that J. R. Oppenheimer was sure that quan- 
tum theory provided a complete solution and 
description but added, "I have talked very little 
to him about it." Einstein felt sure that the final 
correct theory must start with general relativity 
(although he said that his own attempts in this 
direction were probably wrong). 

The difficulties in quantum theory are becom- 
ing very acute in nuclear theory which Einstein 
considered hopeless in its present state. He felt 
that just the multiplication of facts and experi- 
mental data in nuclear physics would not clarify 
the situation or lead to a final correct theory. 
This is in marked contrast to the prevalent view 
that experimental facts will utimately reveal 
regularities and thus give the hints that will lead 
to a theoretical solution. He disagreed com- 
pletely with this view and emphasized again that 
even in atomic problems the quantum theory 
description is unsatisfactory. We talked about 
the big machines used in nuclear physics, and he 
feared a real danger from these for the scientific 
method. They make us "slaves to the means," 
and new ideas would be lost or never found. 28 

I asked if he had seen Dirac's article in Nature 29 
on the aether, and he said no and asked me about 

28 One must remember that this was 10 years ago ! 
*>P. A. M. Dirac, Nature 168, 906 (1951). 

it. 1 told him a little, and when I mentioned the 
relationship of the Uncertainty Principle to the 
impossibility of denning a unique reference 
direction in space, he said, "I do not like it!" He 
continued to say that if one needed properties 
that are in space before matter, the field equa- 
tions, etc., are introduced, then you would need 
an aether but that this need does not exist. He 
went on to explain why "Maxwell's equations are 
not reality," but I did not follow this. 

He then recalled Synge and his work and asked 
me if he were not somewhat of a philosopher. He 
again said that more experiments were not 
necessary, and results such as Synge might find 
would be "irrelevant." He told me not to do any 
experiments of this kind. 

As I left Einstein, 1 realized that he seemed 
much older. His eyes still had the deep smile but 
were not as keen as before. His hands were a 
little feeble, and when I asked him if he still 
played the violin (a Brahms' score was on his 
desk) he said, "No, my fingers don't work any- 
more. " I thanked him for his time, but he waved 
his hands in protest. Then we shook hands, he 
smiled, and I left. 

IV. 24 October 1952 

It was a beautiful October day, and I walked 
down Mercer Street to Professor Einstein's home 
which is number 112. Einstein's secretary greeted 
me and led me upstairs and to the rear of the 
house to Professor Einstein's study. This was an 
attractive simple room with open white book- 
shelves on two sides filled in rather a disordered 
fashion with books, reprints, and papers. 
Towards the back of the room large windows look 
out on a yard where today the trees are in their 
last autumn foliage. I was struck at once by a 
fine portrait of Maxwell on the wall and by 
another of Faraday. Professor Einstein was 
sitting on the adjacent porch when I entered, but 
he immediately came into the study and greeted 
me in a very friendly way. He asked me to be 
seated by his desk, and I then told him of the 
plans at Case to celebrate the 100th birthday of 
Michelson at which time I was to speak on his 
work and especially about the interferometer 
experiments. He smiled broadly and expressed 
real satisfaction that we were doing this. He said, 
"I always think of Michelson as the artist in 



science. His greatest joy seemed to come from the 
beauty of the experiment itself and the elegance 
of the method employed. He never considered 
himself a strict 'professional' in science and in 
fact was not — but always the artist." 

I asked Professor Einstein where he had first 
heard of Michelson and his experiment. He re- 
plied, "This is not so easy, I am not sure when I 
first heard of the Michelson experiment. I was 
not conscious that it had influenced me directly 
during the seven years that relativity had been 
my life. I guess I just took if for granted that it 
was true." However, Einstein said that in the 
years 1905-1909, he thought a great deal about 
Michelson's result, in his discussions with 
Lorentz and others in his thinking abdut general 
relativity. He then realized (so he told me) that 
he had also been conscious of Michelson's result 
before 1905 partly through his reading of the 
papers of Lorentz and more because he had 
simply assumed this result of Michelson to be 

I told Einstein of my father's report as a 
student at Western Reserve University that the 
Michelson-Morley experiment was considered to 
have been a failure and that Morley was in a 
certain sense an object of pity. He shook his head 
vigorously at this and said, "No one should have 
said that! Many negative results are not highly 
important, but the Michelson experiment gave a 
truly great result which everyone should under- 

Professor Einstein felt that the work of 
Lorentz should be studied much more by present- 
day physicists. He said that the Maxwell electro- 
magnetic theory had not been left in good form 
and really only applied to a vacuum. This was 
made clear by the work of Lorentz who showed 
that electric field and displacement must always 
be related by the properties of the medium, and 
so theory must assume or find these properties 
before it can proceed. Lorentz's contributions to 
this subject were, in Einstein's opinion, his great 
achievement. His proof that essentially there are 
not four fields but rather two is an achievement 
of the greatest historical importance. 

Professor Einstein told me that he felt that the 
history of the development of ideas in science is 
neglected. He was not interested in the history of 
data — when, who did this, etc., — but in the 

tracing of the evolution of ideas. "Most scientists 
today do not seem to realize that the presenl 
position of science can have no lasting signifi 
cance." I asked him if it was not probable that 
the next great advances in physics would be 
farther in the future than most "planners" would 
admit, and he laughed and said, "Yes, yes they 
are all trying to get their results too cheap!" 

Einstein then told me again how beautiful he 
considered "Michelson's rotation of the earth 
experiment." (Michelson-Gale experiment). He 
considered this as one of the most beautiful of all 
the experiments in physics and after the Michel- 
son-Morley experiment, he considered it as 
Michelson's greatest achievement. As Einstein 
said, "Michelson could not stop and reverse the 
rotation of the earth, so he accomplished the 
same result by using a big path and a little path. 
(Gestures). It is really not self-evident how this 
could give the same result as stopping the earth." 
(Here Einstein smiled with real joy.) 

Einstein also mentioned the earth-tide ex- 
periment 30 which he also liked very much. "This 
experiment was out of his (Michelson's) line, but 
an optical principle suggested itself to him and 
made the measurement succeed." 

I asked Einstein if he had any explanation for 
the fact that Michelson first repeated the Fizeau 
moving water experiment at Case before taking 
up the repetition of his own Potsdam experiment. 
Einstein said that it seemed very natural to him 
that Michelson would take up the Fizeau experi- 
ment and that this simply proved, "that the 
whole problem was in Michelson's mind and that 
he was thinking deeply on all aspects of it. The 
Fizeau experiment and result was so funda- 
mental that an improved repetition of it would in 
any case be highly desirable." I asked Einstein if 
he felt there had been any serious doubt at the 
time about Fizeau's result, and he replied, "Oh, 
every experiment should be repeated and refined 
whenever possible." Several times he said, "I 
really loved Michelson." 

I told Einstein that in Michelson's lectures on 
optics to his students at Case he had not men- 
tioned the results of his own Potsdam experiment 
or even described his own form of interferometer. 
Einstein thought this was natural, as a teacher 

30 A. A. Michelson and H. G. Gale, J. Geol. 27, 595 (1919). 



should tell his students only the completely 
established facts. He added that if he were to give 
lectures on theoretical physics, he would omit all 
reference to his own more speculative work and 
would reserve this for listeners who were more of 
the type of "connoisseur," and who would 
realize that many of the points were still not 
finally settled. 

I asked Professor Einstein about the three 
famous 1905 papers 31 and how they all appeared 
to come at once. He told me that the work on 
special relativity "had been his life for over seven 
years and that this was the main thing." How- 
ever, he quickly added that the photoelectric 
effect (he could not for a moment recall the 
English word) paper was also the result of five 
years pondering and attempts to explain Planck's 
quantum in more specific terms. He gave me the 
distinct impression that the work on the Brown- 
ian movement was a much easier job. "A simple 
way to explain this came to me, and I sent it 
off."* 2 

I mentioned that the parts of the Michelson- 
M or ley apparatus are lost and that even the 
exact place where the experiment was performed 
is not entirely certain. To this he smiled and 
shrugged and reminded me that physicists do not 
collect and preserve in the sense of old book 
collectors but that the ideas are the things of 
permanent value. 

Einstein told me that Michelson did not like 
the relativity theory. He told Einstein this and 
he also heard it from others. Einstein laughed and 
added, "You know we were very good friends!" 
Michelson said to Einstein that he was a little 
sorry that his own work had started this "mon- 
ster." Einstein then went on to tell me how 
natural this attitude would be in Michelson and 
that it was due simply to the fact that Michel- 
son's love was to experience phenomena directly 
and that as a result he did not like abstractions. 
I commented that in a certain sense this was 
similar to Goethe's attitude toward color theory. 
To this Einstein replied, "Oh Michelson's 
attitude was not that extreme or he would not 
have been a physicist!" He also added that for 

'i A. Einstein, Ann. Physik 17, 132, 549, 891 (1905). 

32 Of course Einstein worked on problems of the Brown- 
ian Movement a great deal. See his collection of papers 
edited by R. Fiirth (Methuen and Company, Ltd., London, 

Goethe every observation of Nature was a deep 
and direct personal psychological experience and 
that he would not permit the abstractions of 
science to interfere. Much of Goethe's description 
of color is very useful, and up to the point where 
he simply attacked Newton blindly, he made real 
contributions to the subject of colors, especially 
for art. 33 

Einstein talked to me a little about quantum 
theory and added, "Here I am a heretic you 
know (laughed), but someday I believe my 
views will be found true. God did not invent the 
Science of Probability you know!" He spoke very 
highly of Bohm's work but was sure it is wrong. 
"He got his results too cheap." Einstein told me 
that Bohm was not reappointed because he 
refused to testify against other people. Einstein 
spoke very bitterly about the "dirty work" of the 
Rosenbergs' relative who saved his life with 
theirs. About publicity Einstein told me that he 
had been given a publicity value which he did not 
earn. Since he had it he would use it if it would do 
good; otherwise not. He looked mostly at me 
during the conversation, but occasionally his 
eyes looked far out into the autumn leaves. As he 
thought his great eyebrows and the top of his 
head would move, and then his eyes would 
brighten again to tell me something more. 

It was now time for me to leave, and I thanked 
him and will treasure the memory of him sitting 
with a blanket over his knees, his great deep 
smile, his boyish laugh and the sincere friendli- 
ness of that heart and mind. 

He came to the door of his study as 1 left. He 
shook my hand and smiled and thanked me for 
coming. Miss Dukas was standing in the hall as 
I came out. I hope I did not tire him. 

V. 11 December 1954 

Arrived in Princeton on the 10:45 train from 
New York and called Einstein's secretary from 
the Princeton Inn. She told me that Professor 
Einstein wanted to see me but that the doctor 
was there and would I be willing to come in a 
half-hour. I, of course, agreed and arrived at 112 
Mercer Street about 11:30. I left my coat and 
briefcase in the lower hall and Miss Dukas led 
me upstairs and to the back of the house into 

33 J. W. von Goethe, Nachtrage zur Farbenlehre (1810). 



Professor Einstein's study. He arose from his 
chair, shook hands and greeted me in a very 
friendly manner. He began our conversation by 
telling me that he found our arguments convinc- 
ing and "a very fine paper." 84 He then "told me a 
story." At a meeting at the Institute for Ad- 
vanced Study several years ago, they discussed 
Miller's results and Einstein had commented, 
"God is hard on us, but He is not malicious! 36 
Surely there is an explanation for Miller's re- 
sults." (Much laughter by Professor Einstein.) 
Einstein told me again that he was sure we had 
found this, and that everyone was pleased. I 
mentioned that Professor Dyson had made a 
valuable suggestion which we had used to 
improve our correlations with temperature 
conditions. Einstein asked me to tell him 
about Dyson's suggestion, and I discussed the 
AT=Av|f-r t -l, (*= 1,2,3,4). Einstein thought 
this a good suggestion and asked how it worked 
out. When I told him rather well in all but one 
case he replied, "You would expect that!" I told 
him that Professor Miller had given me his data 
and that I was pleased that we could carry out 
his wishes and look into it a little more. He again 
told me that he thought we had settled the 
problem at last. He then told me that he felt 
making the apparatus large was a mistake. "You 
make your troubles bigger and gain so little." He 
also asked me why no one had used vacuum in 
the light paths to get away from temperature 
effects. I told him I did not know but that Joos 26 
had gone pretty far and that by using helium, 
Kennedy 36 had accomplished much the same 

When I began to tell him why I had felt it 
necessary to get into the "frame of mind" that 
suggested going to Mount Wilson, he empha- 

34 This was the final draft of the paper subsequently 
published by, R. S. Shankland, S. W. McCuskey, F. C. 
Leone, and G. Kuerti, Revs. Modern Phys. 27, 167 (1955). 

35 Over a fireplace in Princeton's Fine Hall are almost 
these same words of Einstein : "Raffiniert ist der Herr Gott, 
aber boshaft ist er nicfit." 

36 R. J. Kennedy, Proc. Natl. Acad. Sci. U. S. 12, 621 
(1926) ; Astrophys. J. 68, 361 (1928). 

tically agreed. "You could not properly compre- 
hend the work unless you did this." However, he 
added that the idea that a bigger "aether wind" 
would exist on a mountain had always been 
impossible to bring into a picture with the facts 
of astronomical aberration. 

We then chatted briefly about Michelson, and 
he again told me that he considered him a 
"wonderful man." "Of course," Einstein added, 
"He told me more than once that he did not like 
the theories that had followed from his work!" 
(Much laughter by Professor Einstein.) 

We looked out of his windows to the bare 
trees of the December land, and then I felt I had 
stayed long enough. I asked him not to rise as I 
took my leave, but of course he did. I paused to 
look at the pictures on his study wall of Faraday 
and Maxwell. He spoke highly of each and said 
he especially liked the picture of Faraday. I told 
him I had his latest book and had enjoyed read- 
ing in it, especially the last tribute to Lorentz 
(for his centenary). 37 He became most serious 
and said, "People do not realize how great was 
the influence of Lorentz on the development of 
physics. We cannot imagine how it would have 
gone had not Lorentz made so many great 

We shook hands, and I started down the hall, 
and he followed, telling me (only now!) that he 
was not too well and had a "strong anemia." At 
the top of the stairs we again shook hands, and 
he smiled with that deep and humble expression 
with which he had first greeted me, gripped my 
hand, then raised his hand in a sort of salute and 
said, "Goodbye." 


I am greatly indebted to my colleagues, 
Professors Sidney W. McCuskey, Leslie L. Foldy, 
and Martin J. Klein for advice in the preparation 
of this paper. 

37 A. Einstein, Ideas and Opinions (Crown Publishing 
Company, New York, 1954), pp. 70-76. See also G. L. 
deHaas-Lorentz, H. A. Lorentz (North-Holland Publishing 
Company, Amsterdam, 1957), pp. 5-9. 

July 1973 

Conversations with Albert Einstein. II 

Department of Physics 
Case Western Reserve University 
Cleveland, Ohio 44^06 

(Received 13 February 1973; revised 2 March 1973) 

Professor Einstein's views on the experimental basis for 
relativity theory and his attitude toward quantum me- 
chanics continue to be of general interest. This paper is 
based on notes on these subjects made by the writer after 
each of five visits with Einstein at Princeton during 
1950-1954 and not fully reported or discussed previously. 

In 1963 I reported on five visits with Prof. 
Einstein in Princeton during the period 1950- 
1954. 1 These discussions were published almost 
verbatim, with but little comment by me. They 
have since been referred to in several articles on 
the history of physics, so it now seems appropriate 
to supplement the first publication by a more 
complete discussion of certain statements made 
to me by Prof. Einstein. I would like especially to 
record my impressions of Einstein's views on the 
role of the experiments of Michelson and Morley 
and others in the development of the theory of 
relativity and also to comment more fully on his 
attitude on quantum mechanics. 


Professor Einstein's statements on the Michel- 
son- Morley experiment and its influence on his 
work in the special theory of relativity were made 
on several occasions and are not entirely con- 
sistent; this is not too surprising in view of the 
fifty year interval involved. As this experiment 
was performed in Cleveland and had played a 
central role in the contributions of H. A. Lorentz, 

Henri Poincare, and others, it was only natural to 
ask Einstein what relation it had had to his own 
work. During our discussions he always expressed 
the highest admiration for Lorentz ("the great 
Lorentz," as he said several times) and for his 
publications during the decade prior to 1905. It 
did not occur to me to ask Prof. Einstein about 
Poincare and his influence on his work, but I have 
since learned from Miss Helen Dukas, Prof. 
Einstein's secretary, that they had very little 
correspondence. In the Einstein archives at 
Princeton there is a letter of recommendation 2 
which Poincare wrote for Einstein in 1911; 
however, it does not specifically mention Einstein's 
contributions to the special theory of relativity. 
I have regretted that I did not ask Prof. Einstein 
about Poincare for he would certainly have given 
me detailed answers to any questions and made 
clear the relationship of his own work to that of 
Poincare, as he did with Lorentz. It is well 
established that during Einstein's years in the 
Swiss Patent Office at Berne (1902-1909) he was 
the leader in an evening study group (including 
Maurice Solovine and Conrad Habicht) called 
"Olympia," which was active from 1902 through 
1905. Books which they studied in detail included 
Ernest Mach's Science of Mechanics, Dedekind's 
work on Numbers, and Poincare's La Science et 
L'HypotheseJ The latter work discusses the 
Michelson-Morley experiment and includes Poin- 
care's thoughts on the principle of relativity, both 
for uniform motion and accelerated systems. It 
thus seems clear that Einstein, who had already 
published several original research papers in the 
Annalen der Physik in the period 1900-1905, was 
acquainted with some of Poincare's contributions 
to the principle of relativity, as he was with the 
writings of Lorentz. 3 

Professor Einstein told me several times during 
our talks in Princeton that he had learned of the 
Michelson-Morley experiment through the writ- 
ings of H. A. Lorentz. It was my understanding 
during our talks that Prof. Einstein was well 
aware of the null results of a wide range of both 
first order (v/c) and second order (v/c) 2 aether- 
drift experiments conducted throughout the 19th 

AJP Volume 41 / 896 

R. S. Shankland 

century. This is clearly substantiated by the 
following statement in his famous 1905 paper 4 : 
. . the unsuccessful attempts to discover any 
motion of the earth relative to the 'light medium,' 
suggest that the phenomena of electrodynamics as 
well as mechanics possess no properties correspond- 
ing to the idea of absolute rest. They suggest 
rather that as has already been shown to the first 
order of small quantities, the same laws of electro- 
dynamics and optics will be valid for all frames of 
reference for which the equations of mechanics 
hold good . . . ." The unsuccessful attempts clearly 
refer to the (v/c) 2 experiments; among these, the 
Micheison-Morley experiment was the most 

It is unlikely that he had studied the details of 
the technique of the various experiments, but he 
probably knew more about these than might be 
assumed. I found his interest in and knowledge of 
the essential features of the apparatus used by 
Michelson and Morley, Fizeau, Zeeman, Sagnac, 
Harress, Tomaschek, and Michelson and Gale 
to be much more than I had anticipated would be 
the case. 

The several statements which Einstein made to 
me in Princeton concerning the Micheison-Morley 
experiment are not entirely consistent, as men- 
tioned above and in my earlier publication. His 
statements and attitudes towards the Micheison- 
Morley experiment underwent a progressive 
change during the course of our several conversa- 
tions. I wrote down within a few minutes after 
each meeting exactly what I recalled that he had 
said. On 4 February 1950 he said, "... that he 
had become aware of it through the writings of 
H. A. Lorentz, but only after 1905 had it come to 
his attention." But at a later meeting on 24 
October, 1952 he said, "I am not sure when I first 
heard of the Michelson experiment. I was not 
conscious that it had influenced me directly during 
the seven years that relativity had been my life. 
I guess I just took it for granted that it was true." 
However, in the years 1905-1909 (he told me) 
he thought a great deal about Michelson's result 
in his discussions with Lorentz and others, and 
then he realised (so he told me) that he "had been 
conscious of Michelson' s result before 1905 partly 
through his reading of the papers of Lorentz and 
more because he had simply assumed this result of 
Michelson to be true." Since there are these 

conflicting statements it may be of interest to 
comment further on this situation. 

When I first called on Professor Einstein in 
Princeton on 4 February 1950, he was unac- 
quainted with me and may possibly have wondered 
if I had not come as the successor of Professor 
Dayton C. Miller at Case to talk about Miller's 
"aether drift" experiments at Mount Wilson. 
These were certainly on my mind, but at that 
first meeting my primary objective was to ask him 
about the two Micheison-Morley experiments 
performed at Cleveland in 1886 and 1887. But 
before my views became clear to him, Prof. 
Einstein volunteered a rather strong statement 
that he had been more influenced by the Fizeau 
experiment on the effect of moving water on the 
speed of light, and by astronomical aberration, 
especially Airy's observations with a water filled 
telescope, than by the Micheison-Morley experi- 
ment. This keen interest in the Fresnel-drag of 
moving water had been shared by many workers 
on the "aether problem," For example, at the 
"Baltimore Lectures" of Lord Kelvin (then 
Sir William Thomson) in 1884, both he and Lord 
Rayleigh, who was present, urged Michelson and 
Morley to repeat the Fizeau experiment as an 
essential preliminary to their more famous 
Micheison-Morley experiment. Their interest was 
to clarify the effect of the postulated Stokes drag 
of the aether by the earth and the resulting 
decrease in the expected velocity of the aether 
through the interferometer in the Micheison- 
Morley experiment. However, the close relation 
of the Fizeau experiment to the relativistic veloc- 
ity addition theorem was the prime reason for 
Einstein's interest in this subject. 

As clearly reported by Max Wertheimer, 6 who 
in 1916 discussed with Einstein the development 
of his ideas in special relativity in great detail, 
it is evident that the importance of the Micheison- 
Morley experiment for Einstein was that it gave 
positive confirmation to his belief that the speed 
of light is invariant in all inertial frames, inde- 
pendent of the motion of source, apparatus, or 
observer. Such invariance in c was necessary for 
his interpretation of Maxwell's equations and for 
his derivation of the Lorentz transformation, as 
well as for his conviction that the "local time," 
first introduced by Lorentz, is indeed the only 
true time for the description of physical phenom- 

896 I July 1973 

Conversations with Albert Einstein. II 

ena. Professor Einstein's statement to me was 
that "at last it came to me that [absolute] time 
was suspect," and that the new absolute for 
physics must be the speed of light in. vacuum, 
rather than space and time. These conclusions, 
and also the relativity principle for uniform 
motion to the greater sensitivity (v/c) 2 than had 
been shown by any previous "aether drift" 
experiments, were strongly supported by the 
Michelson-Morley experiment, which showed no 
change in the speed of light with respect to direc- 
tion and revealed no absolute motion of the inter- 
ferometer through space. It is of interest to note 
that even in 1950 Einstein was concerned with 
the possible periodic changes in c which had 
recently been reported, and asked if I thought the 
effects were real. When I told him I believed they 
were spurious, he seemed obviously pleased. The 
fact that he was so interested in these measure- 
ments in 1950 makes it very difficult to believe that 
he was unaware of any important work bearing on 
the problem in the years before 1905. 

When Prof. Einstein realized that I had not 
come as an advocate for Miller's results his 
attitude became less formal and our conversations 
were much more relaxed. Indeed, it was largely 
his encouragement and advice that made me feel 
it would be desirable for us to make the study 
which finally revealed the cause of Miller's 
periodic fringe shifts. I should add that in doing 
this we were also carrying out the wishes of Prof. 
Miller who died without having resolved the 
question and who had suggested that we restudy 
his data if it were thought desirable. Professor 
Einstein's statements to me about Prof. Miller 
and his experiments were uniformly respectful, 
though it was clear that he felt sure they were in 
error. He also told me that II. A. Lorentz had 
tried without success to explain Miller's results. 

In this connection it is of interest to note that 
in 1921 when Miller first announced the periodic 
fringe shifts in his interferometer experiments on 
Mount Wilson, Einstein was lecturing on relativity 
at Princeton. He told me that it was Miller's 
work that had prompted his remark now inscribed 
in the stone fireplace at Fine Library, "Raffiniert 
ist der Herr Gott, aber boshaft ist er nicht." When 
he learned of Miller's result he travelled to Cleve- 
land to see him and they had a long discussion 
about the Mount Wilson experiments. Professor 

Einstein told me that at that time he did not feel 
sure of a single English word, 1 but Prof. Miller 
could speak German rather fluently, for 
youth in Berea, Ohio, his playmates were the 
children of German Methodist ministers teaching 
at Wallace College (now a part of Baldwin- 
Wallace College) . The writer has a sketch made 
by Prof. Einstein during this visit on 25 April 1921 
indicating how the postulated Stokes drag of the 
"aether" by the earth would become progressively 
smaller with elevation above sea level so that on 
Mount Wilson the expected fringe shifts in the 
interferometer should be considerably greater 
than in the basement laboratory at Cleveland. 
Of special interest on the sheet with Einstein's 
sketch is the word "Fizeau" written by Miller, 
probably because Einstein had discussed the 
Fizeau experiment and its greatly improved 
repetition by Michelson and Morley at Case in 
1886. This notation again emphasizes the im- 
portance that Einstein attached to this experiment 
and proves that even in 1921 he considered the 
phenomenon of the effect of moving water on the 
speed of light as a major observational fact for his 
work on special relativity. By assuming an 
invariant upper limit for the speed of light in 
vacuum, the derivation of the relativistic velocity 
addition theorem, which is closely related to the 
Fresnel drag, follows directly. The word "Fizeau" 
written on Einstein's sketch may also indicate 
that as early as 1921 when Miller's positive result 
seemed definite, Einstein may have been looking 
elsewhere than to the Michelson-Morley experi- 
ment for experimental support for the postulates 
of relativity. It also could mean, as he told me in 
1952, 1 that he had suggested to Miller that the 
Fresnel drag by the Mount Wilson interferometer 
itself would greatly reduce the expected fringe 

When we 6 finally found the cause of Miller's 
periodic fringe shifts to be temperature gradients 
across the interferometer, Einstein was genuinely 
pleased and, in fact, wrote me a fine letter on the 
subject. I only learned after his death that he 
had written to Ehrenfest after Miller's 1921 
announcement, suggesting that temperature effects 
might be responsible for the results; it is curious 
that he never mentioned this to me. Whether he 
had forgotten about it or whether he wanted us to 
find the solution in our own way, I cannot say; 

AJP Volume 41 / 897 

B. S. Shankland 

but of his genuine interest in finding the correct 
answer there can be no doubt. 

It is important to note that in talking with 
M. Wertheimer in 1916, Einstein's references to 
experiments were amost exclusively to the better 
known Michelson-Morley experiment. 5 This was 
five years before Miller's first experiments. This 
writer finds the account of Wertheimer entirely 
consistent with his own notes and recollections of 
Einstein's attitude in 1952 toward the Michelson- 
Morley experiment. 

The writer is convinced on the basis of his dis- 
cussion with Prof. Einstein that he certainly knew 
about the Michelson-Morley result before 1905 
and also was conversant with a wide range of both 
the experimental and theoretical work in the 
physics literature bearing on the "aether problem" 
before 1905. However, the exact relation which any 
specific experiment or the theoretical work of 
other physicists bore to his own creations is not 
possible to determine with certainty; even Ein- 
stein himself was not sure. But to believe that he 
could be unaware of important experiments or 
theoretical developments in the decade before 
1905 is entirely inconsistent with his profound 
understanding of the development of physics, as 
was clearly evident even in his later years. 

It should be noted that in 1905 it was not the 
practice to give specific references in published 
papers as it is today. Many important papers gave 
no references whatever, so the fact that Einstein's 
1905 paper (which has no references) makes no 
explicit mention of the Michelson-Morley experi- 
ment is not in the least unusual. To what degree 
and at what stage of his activities he was directly 
influenced by the work of others, it is now im- 
possible to determine. But I became convinced 
that his interest in the Michelson-Morley experi- 
ments (both those of 1886 and 1887) had existed 
before 1905. 


One of the great puzzles in physics was the 
attitude of Prof. Einstein toward the new quantum 
mechanics developed during the years after 1925. 
His position was strange not only because of his 
great contributions to physics in general, but 

especially so in view of his leading role in the 
development of the old quantum theory from 1905 
to 1925, when his photoelectric theory, photon 
hypothesis, the concept of induced transitions, 
the first quantum theory of the specific heat of 
solids, and the Bose-Einstein condensation and 
statistics were all major achievements leading to 
the new quantum mechanics. However, when it 
became clear that the new theory had essential 
statistical elements, then Einstein turned com- 
pletely against it and for the remainder of his life 
was an active opponent. 

There is, of course, no way to determine with 
certainty why this change of heart took place. 
But we can recall that during the years 1919- 
1925 following Eddington's successful eclipse 
confirmation of the deflection of starlight by the 
sun, Einstein suddenly became a world figure 
and began lecturing and working for political 
causes that required a significant fraction of his 
time and energy. It was in this period that the 
new quantum mechanics was developed by Bohr, 
Heisenberg, Pauli, Dirac, Schrodinger, Born, and 
others, without Einstein having a major role. 
Nevertheless, during this period he had main- 
tained an active interest. He was one of the first 
to hail the discovery of the Compton effect; here 
his opposition to probability theories first strongly 
appeared when he disavowed the statistical theory 
of Bohr, Kramers, and Slater 7 as a valid descrip- 
tion of this scattering phenomenon. Even when 
the Compton effect was shown to give a clear 
example of the Heisenberg uncertainty principle, 
Einstein was not won over, although enthusiastic 
for its support of the photon theory of radiation. 
But even his earlier use of statistical methods to 
predict the existence of photons traveling with 
energy hv did not affect his attitude toward the 
new quantum mechanics and especially its 
statistical features toward which he remained 
consistently hostile. 

This greatly influenced his relations with Niels 
Bohr and the "Copenhagen School." Although 
Bohr and Einstein were uniformly courteous at 
their meetings and in correspondence, they both 
at times became highly emotional in their views on 
the basic correctness and completeness of the 
quantum-mechanical description of nature. Ein- 
stein made statements to the writer which were 
very strong in his criticisms of Bohr, Heisenberg, 

898 I July 1973 

Conversations with Albert Eimtein-II 

Dirac, Oppenheimer, and others who shared their 
views. Even Dime's relativistic development of 
quantum theory failed to alter Einstein's opinion 
in statements he made to me. We also know from 
friends who studied in Copenhagen that Prof. 
Bohr, in spite of his extremely polite and detailed 
refutations of the various quantum paradoxes 
proposed by Einstein, was often very emotional 
on this subject. Bohr even became highly critical 
of Bohm's work on "hidden variables," and 
considered his attempt for a deterministic picture 
to be philosophically a step backward. 

Recent experiments at Berkeley by E. D. 
Commins and his research students 8 have shown 
that the correlation in linear polarization between 
two photons emitted in an atomic cascade is in 
complete agreement with quantum mechanics 
and in direct conflict with all "hidden variable" 
theories which have been proposed to give an 
underlying deterministic structure such as Einstein 
held to be essential for a complete theory. 9 

The discussions between Einstein and Bohr at 
Solvay Conferences and elsewhere of the paradoxes 
by which Einstein hoped to reveal basic defects 
in quantum mechanics are highly interesting and 
clarify many subtle points. But it is clearly 
evident that time and again Bohr successfully 
defended the quantum mechanical description of 
nature against Einstein's criticisms. One of the 
most dramatic of these exchanges is that where 
Bohr used the general theory of relativity to 
explain a paradox proposed by Einstein at their 
last Solvay Conference meeting in 1930. 10 

The question has often been asked : How would 
Einstein's attitude toward the unified field theory 
have been affected by the problem of including the 
weak and strong nuclear interactions; and especi- 
ally how would he have reacted to the failure of 
parity and other invariance principles. He, of 
course, did not discuss this, but it seems to me 
that since his basic philosophy was always directed 
toward the unification of physics, he would have 
maintained his faith that an all embracing unified 
field theory would ultimately be found. He did 
express the strong conviction to me that the present 
lack of success is due to approximation methods 
that fail to reveal true insights into phenomena, 
that only when great advances in mathematics 
make rigorous solutions possible will significant 
progress be made in theoretical physics, and that 

"the final solution must start with general 

It was clear that Prof. Einstein (in his state- 
ments to me) regarded quantum mechanics as a 
valid computational tool, but he could never 
accept the philosophical implications of its 
statistical basis or believe it was a complete 
description of nature. He felt sure that eventually 
a foundation would be found for quantum 
mechanics that would restore causality and elim- 
inate the uncertainty principle and the statisti- 
cal description and provide a complete theory. 
This viewpoint emphasizes the fact that Einstein 
was at heart a classical physicist. His relativity 
theories were the capstone of the classical physics 
of the 19th century, and the complete break with 
this structure made by the new quantum me- 
chanics appeared to be too much for Einstein to 

Today, the majority of physicists have not been 
greatly influenced by Einstein's attitude toward 
the new quantum mechanics, but there must 
nevertheless be a lingering question that some 
elements of his position may yet prevail, eventu- 
ally to influence future developments. However, 
certain points are clear. In the development of 
physics which led to the theory of relativity, there 
had gradually accumulated basic paradoxes and 
conflicts between theory and experiment that 
were only finally resolved by the theory of rela- 
tivity. These included the null result of the 
Michelson-Morley experiment, the Fizeau and 
Michelson and Morley measurements of the 
Fresnel drag on light in moving water, an ap- 
parent favored inertial frame for Maxwell's 
equations, certain asymmetries in electrodynamics 
that did not seem inherent in the phenomena, etc. 
These finally pointed the way to new concepts of 
space and time in physics, leading at first to the 
special theory of relativity and then to the general 
theory of relativity and gravitation. 

Other paradoxes in physics were finally resolved 
only by the development of the new quantum 
mechanics. Chief among these were the photo- 
electric effect, the Compton effect, phenomena 
that required wave or particle properties for radia- 
tion, electron diffraction and the wave nature of 
matter, the anomalous Zeeman effect, the Stern- 
Gerlach experiment, the existence of discrete 
energy states and transitions in atomic and 

AJP Volume 41 / 899 

R. S. Shankland 

molecular systems, and others. These paradoxes 
and contradictions were only removed with the 
advent of quantum mechanics. 

Today the situation is entirely different. At 
present there seem to be no basic paradoxes or 
conflicts between theory and experiment of the 
nature that suggest that quantum mechanics is 
wrong. To be sure, there are great difficulties, but 
these can be viewed as largely computational in 
nature and not related to the basic validity of 
quantum mechanics itself. The development of 
more powerful forms of mathematics may enable 
many of these problems ultimately to be solved. 
The present difficulties in the application of 
quantum mechanics chiefly involve such factors 
as the lack of detailed and certain knowledge of 
the nuclear force and things of that nature and 
are not inherent in quantum mechanics. Even the 
failure of invariance principles, such as "C," 
"P," and £i CP" in no way affect the validity of 
quantum mechanics but merely affect the forms 
of the Hamiltonian that can be employed in the 
solution of specific problems. 

Einstein's attitude toward quantum mechanics 
was well known but for the record we give some 
of the statements he made to me during my visits 
in Princeton. These are listed here out of context 
but they serve to show the depth of feeling for 
the convictions he held. In making these state- 
ments to me, Prof. Einstein often exhibited great 
emotion and there was certainly no question that 
his opposition to quantum mechanics was very 

Atomistic phenomena must fit into a unified 
field theory. 

You know I am in disagreement with most 
of my colleagues on the quantum theory. 

They are not facing the facts! 

They have abandoned reason! [with great 
emphasis 0 

Quantum mechanical physics avoids reality 
and reason! 

Bohr's thinking is clear but when he 
begins to write he becomes very obscure 
and he thinks of himself as a prophet. 

Bohr always speaks ex cathedra. 

On Quantum Theory I am in the opposition. 

The \p functions do not represent reality. 

Quantum mechanics is a brilliant shortcut 
which successfully avoided many of the 
difficulties and the hard work which the final 
correct theory must face and solve. 

Bohm got his results too cheap. 

I have talked very little with Oppenheimer 
about it. 

The final correct solution must start with 
general relativity. 

Here in quantum mechanics I am a heretic, 
you know [laughed] but someday I believe 
my views will be found true. God did not 
invent the science of probability, you know. 

In closing this account, I would like to express 
my admiration for Professor Einstein in words of 
one of the greatest poets 11 : 

And now his work is done. It will endure, 
We trust, beyond Jove's anger, fire and 

Beyond Time's hunger. It will be borne 
Above the stars, and shall be living, always. 

* This account was given during 1972-1973 for physics 
colloquia at Purdue University; Wilmington, Delaware 
R.E.S.A.; Rensselaer Polytechnic Institute; and Indiana 
University. It is a pleasure to acknowledge my thanks for 
the helpful discussions at these meetings, and also with 
my colleagues at Case Western Reserve University and 
Prof. Luis W. Alvarez. 

1 R. S. Shankland, Amer. J. of Phys. 31, 47 (1963). 

2 See Albert Einstein by Carl Seelig for Poincare's letter 
in French on p. 163 in the original 1954 edition; in the 
English edition, Savill translation, pp 134-135 (Staples, 
London, 1959). See also p. 57 of the English edition for 
"Olympia" reading list. 

* For an excellent, balanced, and detailed discussion of 
the contributions of Lorentz, Poincar£, Einstein, and 
Minkowski to the development of the special theory of 
relativity, see G. H. Keswani, British J. Phil. Sci. 15, 286 
(1965) ; 16, 19, 273 (1965-66). See also, "Poincare's Rendi- 
conti Paper on Relativity" by H. M. Schwartz, Amer, J. 
Phys. 39, 1287 (1971); 40, 862 (1972); 40, 1282 (1972). 

* A. Einstein, Ann. der Physik 17, 891 (1905) , Italics are 

900 / July 197S 

Conversations with Albert Einstein- 1 1 

6 M. Wertheimer, Productive Thinking (Harpers, New 
York, 1945, 1959), Chap. 7 on "Einstein: The Thinking 
that Led to the Theory of Relativity." 

6 R. S. Shankland, S. W. McCuskey, F. C. Leone, and 
G. Kuerti, Rev. Mod. Phys. 27, 167 (1955). 

* N. Bohr, IT. A. Kramers, and J. C. Slater, Phil. Mag. 
47,785 (1924). 

8 C. A. Kocher and E. D. Commins, Phys, Rev. Let- 

ters, 18, 575 (1967) ; S. J. Freedman and J. F. Clauser, 
Phys. Rev. Letters 28, 938 (1972). 

3 A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 
47, 777 (1935). 

10 Niels Bohr in Albert Einstein, Philosopher-Scientist, 
edited by P. A. Schlipp, (Library of Living Philosophers, 
New York. 1949), pp. 224-228. 

11 Ovid, Metamorphoses XV, Epilogue. 


Comment on "Conversations with Albert 
Einstein. II" 

R. S. Shankland 

Department of Physics 

Case Western Reserve University 

Cleveland, Ohio 44106 

(Received 20 May 1974; revised 7 August 1974) 

Several readers of the article on "Conversations with 
Albert Einstein. II," published in the July 1973 issue of 
this Journal, 1 have expressed interest in the work of Poin- 
care, which was studied by Einstein and the Olympia 
Club in Bern prior to 1905. This letter gives the specific 
reference alluded to on p. 895 of Ref. 1 . 

The following statement appears on p. 201 of the 1903 
edition of Poincare's book La Science et VHypothese 2 
(the italics are mine). 

Et maintenant il faut qu'on me permette une di- 
gression; je dots expliquer, en effet, pourquoi je ne 
crois pas, malgre Lorentz, que des observations 
plus precises puissent jamais mettre en evidence au- 
tre chose que les deplacements relatifs des corps 
materiels. On a fait des experiences qui auraient du 
deceler les termes du premier ordre; les resultats ont 
ete negatifs; cela pouvait-il etre par hasard? Per- 
sonne ne l'a admis; on a cherche une explication 
generate, et Lorentz l'a trouvee; il a montre que les 
termes du premier ordre devaient se detruire, mais 
il n'en etait pas de meme de ceux du second. Alors 
on a fait des experiences plus precises; elles ont 
aussi ete negatives 3 ; ce ne pouvait non plus etre 
1 'effet du hasard; il fallait une explication; on l'a 
trouvee; on en trouve toujours; les hypotheses, e'est 
le fonds qui manque le moins. 4 

This statement clearly distinguishes between the vie and 
v 2 /c 2 "aether drift" experiments that were so much in the 
scientific literature of that day. While there is no explicit 
mention of the Michelson-Morley experiment by name, it 

seems to me that the words in italics (mine) clearly refer 
to their result. It was not then the usual practice to burden 
research papers with footnotes and references to well- 
known results, and the Michelson (1881) and the 
Michelson-Morley (1887) experiments had been discussed 
repeatedly in the literature from 1881 on into the 20th 
century. Often their result was referred to in a very gen- 
eral way as in Poincare's book, although in his 5 June 
1905 paper 5 Poincare was explicit about Michelson (but 
not Morley). 

Einstein, in his famous 1905 6 paper (which has no 
specific references), refers to both vie and v 2 /c z experi- 
ments in much the same way as Poincare had done. Ein- 
stein's words are as follows (the italics, again, are mine). 

Beispiele ahnlicher Art, sowie die misslungenen 
Versuche, eine Bewegung der Erde relativ zum 
"Lichtmedium" zu Konstatieren, fiihren zu der 
Vermutung, dass dem Begriffe der absoluten Ruhe 
nicht nur in der Mechanik sondem auch in den 
Electrodynamik keine Eigenschaften der 
Erscheinungen entsprechen, sondem dass vielmehr 
fur alle Koordinaten systeme, fur welche die 
mechanischen Gleichungen gelten, auch die 
gleichen elektrodynamischen und optishen Gesetze 
gelten, wie dies fur die Grossen erster Ordnung be- 
reits erwiesen ist. 

J R. S. Shankland, Am. J. Phys. 41, 895 (1973). 

2 H. Poincare, La Science et VHypothese (Flammarion, Paris, 1903). 

3 This clearly refers to the v 2 /c 2 experiments of Michelson and Morley 

and also, possibly, to those of Trouton and Noble [Philos. Trans. R. 

Soc. Lond. 202, 165 (1903)] and of Lord Rayleigh [Philos. Mag. 

4, 215 (1902)]. 

4 One detects in these last words Poincare's coolness to the ad hoc na- 
ture of the original Fitzgerald-Lorentz contraction hypothesis. This 
was in 1903 before its later formulation by Lorentz in 1904. 

& H. Poincare, C. R. Acad. Sci. (Paris) 140, 1504 (1905). In this paper 
Poincare first named the Lorentz transformation and proved that it is 
a mathematical group and then extended the 1904 theory of Lorentz 
to obtain the transformations for electric charge and electric current 

"A. Einstein, Ann. Phys. (Leipz.) 17, 891 (1905).